During exercise, an individual's heart rate tends to increase steadily until a. the athletic activity is completed and the cool down begins b. the individual begins to use advanced breathing techniques c. a level of consistent intensity has been reached d. none of the above select the best answer from the choices provided. a b c d

You isolate an infectious substance capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. you have four methods at your disposal to analyze the substance and determine the nature of the infectious agent.i. treat the substance with enzymes that destroy all nucleic acids and then determine whether the substance is still infectious.ii. microscope.iii. culture the substance on nutritive medium, away from any plant cells.iv. treat the sample with proteases that digest all proteins and then determining whether the substance is still infectious.if you already know that the infectious agent was either bacterial or viral, which method(s) listed above would allow you to distinguish between these two possibilities? a) ib) iic) ii or iiid) iv